Cranes

ABSTRACT

The invention disclosed concerns a telescoping crane having a number of sections which nest one within the other in a contracted condition. Two sets of latch mechanism are disclosed one to hold the telescoped sections in their extended condition and the other to hold them in their contracted condition. The latter mechanism ensure that the tension in the cable used to telescope the sections outwards raises the uppermost section last.

United States Patent 91 Vonck CRANES [76] Inventor: Willem Frederik Vonck, 5 Coombe abandoned.

Foreign Application Priority Data Feb. 12, 1969 Great Britain ..7,645/69 [52] US. Cl ..52/12l, 212/55 [51] Int. Cl. .1504]! 12/34 [58] FieldofSearch ..5 2/l15, l2l;212/55 1 Apr. 17, 1973 [56] References Cited UNITED STATES PATENTS 2,942,700 6/1960 Darmenter ..52/l2l 3,398,492 8/1968 Nansel ....212/ss r 2,829,741 4/1958 Secberg ..s2/121 Primary Examinerl-la.rvey C. l-lornsby Attomey-Watson, .Cole, Grindle & Watson ABSTRACT The invention disclosed concerns a telescoping crane having a number of sections which nest one within the other in a contracted condition. Two sets of latch mechanism are disclosed one to hold the telescoped sections in their extended condition and the other to hold them in their contracted condition. The latter mechanism ensure that the tension in the cable used to telescope the sections outwards raises the upper most section last.

3Claims,6DrawingFigures PATENTEU APR 1 1:913

SHEET 1 BF 5 Hal.

INVENTOR WILLEM F. VONCK I wafiou, M,

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ATTORNEYS PATENTEDAPRI T1815 3; 727., 359

SHEETEDFS F/QJ. (a) (b) (c) INVEN'TOR WILLEM F. VONCK BY my), C424. W4UJQLM ATTORNEYS P I APR 1 11913 SHEET h 0F 5 i r x 1 I 1 INVENTO R WILLEM F. VQNCK BY A ATTORNEYS CRANES This is a continuation of application Ser. No. 10,957, filed Feb. 12, 1970, now abandoned. I

This invention relates to cranes and in particular to means for extending and contracting a boom comprising a number of movable sections which are interconnected by an extension cable.

According to the present invention a crane includes a boom, such as a tower or a jib, which boom comprises at least three sections namely first, second and third sections extensible between contracted and extended conditions, of which, when extended, the first is uppermost of the three and the third lowermost, an extension cable extending between the sections and being capable, upon taking in or paying out of the cable, of causing movement of the sections with respect to one another to vary the length of the boom, a first latch mechanism arranged to latch the first section and second section in their mutually contracted condition against movement with respect to each other whilst the first section and the second section are together moved by the extension cable with respect to the third section to lengthen the boom; and a second latch mechanism arranged to latch the second section and third section in their mutually extended condition against movement with respect to each other whilst the first section is moved with respect to the second section, by the extension cable, to shorten the boom.

Preferably the second latch mechanism is releasable by means of a cable connected therewith, which cable conveniently comprises the extension cable. The first latch mechanism may also be arranged to be releasable by applying a predetermined tension to the extension cable, and preferably the first latch mechanism includes means whereby the value of the predetermined tension in the extension cable at which the latch is released may be varied.

Thus in the construction according to the invention a tower is made up from a number of telescopic sections of appropriate cross-section, the largest section being at the bottom of the tower. When raising the tower by taking in the telescoping cable the tendency is for the inner-most section to rise first until it is fully extended and then for the second smallest section to rise carrying with it the already extended smallest section and so on. This sequence of raising sections would be undesirable since as each succeeding section is raised it would carry with it all the already extended smaller sections, making the erection very unstable and would extend the weakest sections first making the tower weak.

By the arrangement of latches according to the invention between adjacent sectionsit is arranged that when the telescoping cable is taken in to raise the tower the section next to the bottom section will move first, tegether with the other telescoped smaller sections therein, and when that section is fully extended the next succeeding smaller section will move, and so on until the last section to extend is the uppermost section.

Similarly when lowering or contracting the tower owing to the weight of the sections of the tower the tendency, when the telescoping cable is released, is for the bottom section to move initially, followed by the next smaller section and so on until the last to telescope would be the lightest top section.

Again the latches provided between each section arrange that when lowering, the lightest top section first telescopes into the succeeding adjacent larger section, then that latter section moves into the next succeeding larger section and so on until the final section to move is that adjacent the bottom stationary section, with all the smaller sections already contracted.

The invention may be carried into practice in a number of ways but one specific embodiment will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic side elevation of a crane of the extensible tower type according to the present invention shown partially extended with certain parts of the tower removed for clarity;

FIG. 2 shows in three stages, in a diagrammatic manner, the extension and contraction of three sections of a tower;

FIG. 3 shows the method of extension of three sections of a tower in a prior proposal;

FIG. 4 is a sectional plan of the tower;

FIG. 5 is a sectional side elevation on theline 5-5 of FIG. 4 with both latch mechanisms in an engaged position, and

FIG. 6 is a view similar to FIG. 5 with one of the latch mechanisms released.

Referring firstly to FIG. 1, this shows a mobile type of crane comprising a chassis 10 mounted on wheels 1 1 and supporting a turntable 12 by means of a slewing ring 13. Upstanding from one part of the periphery of the turntable 12 is a support 15 for the base of a tower generally indicated at 20. The tower is made up of four telescoping sections namely a lower. swection 21 secured to the support 15, and three section s'22, 23 and 24 which are arranged to telescope into and out of one another between a lowered position and an extended position. The upper end of the uppermost section 24 is supported by a derricking cable 26, and carries pulleys 27 and 28 over which extends a hoisting cable 29. The cables 26 and 29 extend'downwards over the end of a so-called A- frame 30 and down to winches (not shown) on the turntable 12.

Reference will now briefly be made to FIGS. 2 and 3. FIG. 2 diagrammatically illustrates a sequence of operations when extending three telescoped tower sections A, B and C according to the present invention. The desired sequence for extension is in the order shown from left to right, i.e., in FIGS. 2(b) the sections B and C are lifted bodily out of section A and thereafter movement takes place towards FIG. 2(0) by the removal of section C from section E4.

This is in contrast to the prior construction illustrated in FIG. 3 wherein three tower sections A, B and C are extended firstly to the FIG. 3(b) position wherein the inner tower C is first lifted out of the tower section B'. Thereafter the two sections B and C are lifted to the FIG. 3(c) position. The normal tendency is for the sequence of FIG. 3 to take place because when raising the tower the taking in of a telescoping cable extending around pulleys on the various sections of the tower for example in the manner shown in FIG. 2 results in tendency for the lowest i.e., the innermost and eventually the uppermost, section to rise first until it is fully extended to the FIG. 3(b) position and then for the second smallest section B to rise carrying with it the smallest section C'. This sequence of raising sections is undesirable since as each section is raised it will carry with it the already extending smaller sections making the erection unstable and the tower weak.

The invention is therefore specifically concerned with providing mechanisms to ensure the sequence of operations of FIG. 2, i.e., the movement of the sections of the tower from FIG. 2(a) firstly to FIG. 2(b) and then to FIG. 2(c) on telescoping upwards and the reverse operation, i.e., from FIG. 2(a) firstly to FIG. 2(b) and thereafter to FIG. 2(a) on lowering. This operation of lowering is also in contrast to the natural sequence of operations in the prior proposal since in general, on contracting a tower, owing to the weight of the sections of the tower the tendency when the telescoping cable is released is for the sections to move from FIG. 3(c) position to FIG. 3(b) followed by movement from FIG. 3(b) to FIG. 3(a).

FIG. 2(0), as well as FIG. 1, diagrammatically illustrate the form of two latch mechanisms by which this sequence'of operations is ensured. A telescoping cable 31 is shown which passes over a pulley 32 at the upper end of the tower section A in FIG. 2 and then around a pair of pulleys 33 at the lower end of the section B and upwards to similar pulleys on the upper end of the section B and the lower end of the section C. Mounted on the underside of each of the sections B and C is a hook 35 which is arranged to co-operate with a detent 36 in the lower end of the next lowest tower section. The details of the manner in which these hooks and detents co-operate to form one of the latch mechanisms is shown in FIGS. 4, 5 and 6 and will be described hereafter.

Referring now to FIGS. 1 and 2 each tower section which extends out of a lower section has associated with it latch mechanisms 41 by which the tower is secured in its extended position against downward movement into the next lower section. These further latch mechanisms 41 are so provided that catches 40 which hold the sections extended are withdrawn in the correct sequence to ensure the lowering of the tower sections in the sequence indicated in FIG. 2. Here again the manner in which the latch mechanisms 41 release the catches 40 in the correct sequence will be described with reference to FIGS. 4 to 6.

Referring now to FIG. 4 this shows part of the three sections 21,22 and 23 of the tower illustrated in FIG. 1. As will be seen, each of the sections is rectangular in plan and is formed by corner posts 45 interconnected by transverse rails 46 and diagonal tubular bracing 47. As shown in FIG. 5 the tower section 2 is shown in its lowered position nested within the tower section 22 for which purpose the tower section 23 rests on brackets 50 secured to the tower section 22. This latter section is however shown in elevated position extended from the outer, lowermost section 21. In other words FIG. 5 represents the relative positions of the sections 21, 22 and 23 which correspond to the relative position of the diagrammatic tower sections A, B and C in FIG. 2(b). In order to maintain the tower sections in this position the catches 40 of which there are four, one at each corner, hook over transverse members 51 of the tower section 21. At this stage therefore the telescoping cable indicated at 31 can be relaxed and the tower will remain in the position shown. The cable 31 is shown passing around two pulleys 33 secured to the lower end of the tower section 22, the lefthand pulley 33 in FIG. 5 being situated slightly further inboard than the righthand pulley for a purpose which will be described.

FIG. 5 illustrates, on a considerably larger scale, the hook 35 which projects downwards from the lower end of the tower section 23 and its co-operating detent 36 which is pivoted at 34 to the next lower section 22. The detent 36comprises a pair of parallel side plates 36A, shown in FIGS. 4 and 5. A transverse latch pin 37 extends between these side plates of the detent 36. The latch pin co-operates with a shouldered surface 38 of the hook 35 when in the connected position of FIGS. 4 and 5. The detent 36 is biassed anti-clockwise in FIG. 5 by means of a spring 55 extending between an abutment 56 on the upper end of the detent 36 and adjustable spring mount 57 secured to one of the diagonal tubular braces 47 of the tower section 23. The lower end of the hook 35 has an inclined member 48 extending downwards from it and affording a ramp surface 39 for co-operation with the pin 37. Accordingly as the tower section 24 is lowered into the tower section 23 the latch pin 37 will engage the ramp surface 39 and move the detent 36 clockwise, compressing the spring 55, until the latch pin 37 can engage on the shouldered surface 38 of the hook 35. Separation of the pin 37 from the surface 38 can only take place by compression of the spring 55 and as will be described the different rates of the springs in the various sections governs the sequence in which the sections will separate.

General reference has been made to the latch mechanisms 41 shown in FIGS. 1 and 2. One of these will now be described in detail with reference to FIGS. 4 and 5. This includes a release bar formed by a pair of parallel vertical plates 60 maintained in spaced apart condition as shown in FIG. 4 by suitable transverse members. The catches 40 are released by the release bar at the desired time.

At their lefthand ends the plates 60 forming this bar are interconnected by a roller 61 around which a run of the telescoping cable 31 extends as shown in FIGS. 5 and 6. In the latched condition of the hooks 40 of FIG. 5 the bar formed by the two plates 60 is in such a position that the run of cable 31 around the roller 61 is kinked slightly as shown at 62. Accordingly a tension in the cable at this time will tend to cause the kinked section 62 to straighten to a vertical position which will therefore tend to move the bar formed by the plates 60 leftwards, in FIG. 5 to the position shown in FIG. 6.

The four catches 40 are each formed integrally as a hooked upper end of a vertical arm 65 of a bell crank 66 pivoted at 72 to the adjacent comer port. The bell crank 66 has lower generally horizontal arm 67 and the pair of catches 40 shown in FIG. 5 are caused to cooperate one with the other by an interconnection generally shown at 68 in FIG. 5. This comprises a tongue 69 on one bell crank co-operating with a recess 70 on the other to allow for pivoting movement of the two bell cranks 66 about their horizontal pivotal connections 72. The righthand bell crank 66 in FIG. 5 is interconnected with a corresponding bell crank for the hook 40 on the opposite side of the framework of this section by means of a rod 75. A similar rod 76 extends between the upper end of the bell crank 66 on the lefthand side in FIG. 5 and the corresponding position on the similar bell crank at the top lefthand corner of FIG. 4.

For each pair of bell cranks 66 on one side of the tower section a compression spring 77 is provided which, via a plate 78, bears against pins 79 and 80 secured to the arms 67 of the bell cranks adjacent the connection 68. The purpose of the spring 77 is to bias the ends of the arms 67 of the bell crank upwards and hence to bias the catches 40 outwards into the operative position of FIG. 5.

FIG. 6 shows the catches 40 withdrawn inwards to a disengaged position. Such movement to the disengaged position has been caused by a tensioning ofthe cable 31 so that the kinked region 62 of FIG. 5 disappears, i.e., the run of cable adjacent the roller 61 on the lefthand end of the bar fonned by the two plates 60 is substantially. vertical. To provide for such disengagement of the catches 40 by leftward movement of the plates 60, these plates are each formed with similar aligned notches 84 cut into their lower sides and arranged to overlie the transverse rod 75. Accordingly the leftward movement of the plate 60 between the positions of FIG. 5 and FIG. 6 will draw the righthand bell crank 66 anticlockwise so carrying with it the other bell crank on the opposite side of the framework by virtue of its interconnection with the rod 75. The interconnections between the pairs of hell cranks formed by the tongues 69 and recesses 70 will cause corresponding movement of the bell cranks on the lefthand side.- Thus the bell crank shown to the left in FIG. 6 will move clockwise about its pivot 72 so as to withdraw the catch 40 in a similar manner.

Between the plate 60 is a second spring mount 85 having an adjusting screw 86. Extending between the spring mount 85 and a plate 87 secured to the detent 36 is a compression spring 88. This compression spring will therefore be compressed as the plate 60 moves from the FIG. 5 to the FIG. 6 position so tending to the plates 60 back to the right. The plates 60 extend through a support 90 within the frame of the section a 2 2. For this purpose the support 90 has an aperture 91. This aperture 91 not only permits sliding movement of the plates 60 horizontally but also a tilting movement of the plates 60 to the chain-dotted line position shown in FIG. 6. The purpose of such tilting movement will be described shortly.

The operation of the crane is as follows. Dealing firstly with the disconnection of two extended sections of tower, as will be required during downward contraction of the tower, it will firstly be assumed that the upper sections 23 and 24 have been telescoped into their desired positions within the section 22 although the section 24 is not shown in FIG. 5 for clarity. Thereafter it will be necessary to release the catches 40 shown in FIG. 5 in order to permit the sections 22, 23 and 24 to be lowered bodily into the section 21. Since the catches 40 have overhanging ends 92 which overlie the outer surface of the associated transverse members 51 it will be appreciated that the catches 40 cannot be withdrawn inwards unless the three tower sections 21, 22 and 23 are lifted slightly. Therefore when the cable 31 is tensioned it will be firstly necessary to raise the tension to such an extent that it will lift the sections 22, 23 and 24 slightly as shown in FIG. 6 in order that the overhanging portions 92 are horizontally clear of the transverse'mer'nbers 5 1. The tension in the cable 31 will then draw the plates 60 to the left andthe interengagement between the notches 64 of these plates and the rods will disengage the catches 40, i.e., move them to the FIG. 6 position. The tension in the cable 31 can now be relaxed gradually to allow the sections 22,23 and 24 to fall bodily into the section 21. There will, nevertheless, be sufficient tension in the cable to maintain the catches 40 in their disengaged position during the initial lowering of the tower sections. However, as the catches 40 pass to a level below the transverse members 51, vertical plates 93 extending upwards to the level of the top of the transverse members 51 will prevent outward movement of the catches 40 even if the tension in the cable is relaxed. Indeed the plates 93' maintain the catches in their disengaged position on upward movement of the tower sections until the catches are clear of the top of the plates 93 and can be biased outwards by the associated spring 77.

Since however, during raising of the tower sections, it will be necessary to maintain a tension in the cable 31 which will at that time hold the plates 60 in their leftward position, it will be necessary to ensure disconnection of the notches 84 of these plates 60 from the rod 75 in order that the catches 40 can move out into-their locking position independently of the plates 60 and the tension in the cable when they reach the desired level. For this purpose the righthand ends of the plates 60 have a roller 95 positioned between them which cooperates with a further vertical plate 96 extending up the side of the next outer tower section. As can be seen in FIGS. 5 and 6 the upper end of this plate 96 is turned outwards to form a cam surface 97. Secured to one of the diagonal tubular braces 47 above the plates 60 is a stop 98. During the initial downward movement of the tower section 22 into the tower section 21 the roller 95 will engage the cam surface 97 which will lift the plates 60 to the chaindotted line position shown in FIG. 6 this movement being permitted by the aperture 91 in the support 90. Thereafter the roller will be forced down on the inside of the plate 96 which will cause the plate 60 to move leftwards slightly. Thereafter the region 99 of the under-surface of the plate 60 indicated in FIG. 6 can rest on the rod 75. Such further leftward movement of the plate 60 will of course move the roller on the lefthand end of the plate 60 away from the cable 31. It will be appreciated that the movement of the plate 60 to the chain-dotted line position will be caused by reaction of the roller 95 against the plate 96, the extent of movement being governed by the position of the stop 98.

Dealing now with upward movement of the sections of tower it is convenient to refer to FIG. 2 bearing in mind that these show, as compared with the remainder of the drawings, the uppermost three sections. Thus section A is equivalent to section 22, section B is equivalent to section 23 and section C is equivalent to section 24. In the position of FIG. 2(a) the two sets of first catch mechanisms shown will be inter-engaged so that the hooks 35 will be engaged by their respective detents 36, and the associated springs 55 of these two mechanisms will be compressed. When a detent is to be released 36 from its associated hook 35, it will be necessary for the tension in the cable 31 to overcome the compression of the associated spring 55. It is to be noted that the shouldered surface of the hook slopes downwards slightly to ensure that the detent can transmit part of the tension to the spring 55 and, as this spring is compressed, so the detent 36 can be released from the hook 35.

Since it is desired that the sections B and C should rise together with respect to section A, i.e., from the FIG. 2(a) to the FIG. 2(b) position the latch mechanism 35-36 between the sections A and B will be required to release at this time without the latch 35-36 between the sections B and C releasing. This is ensured by appropriately adjusting the screws of the spring mounts of the two mechanisms so that the spring 55 on the latch mechanism between the sections A and B in FIG. 2(b) or between sections 21 and 22 in the specific embodiment will release first.

To give an example of the loading which might be required on two springs with such mechanisms, and that each tower section is two-thirds of a ton in weight it can be arbitrarily chosen with the load required to release the lower of the lower detent is one-third of a ton.

Since the load required on the cable to release that detent will also include the weight of say two sections above it, the total tension required to lift these two sections against the action of the spring will be five-thirds of a ton. The tension in the cable will then return to four-thirds of a ton for lifting the two sections bodily out of the lower section. When they have reached their uppermost position it will be necessary to release'the upper of the two springs. The lifting load required will have to be greater than 1 ton. This is arrived at by subtracting the load of the upper section from the lifting load or tension in the cable on release of the lower mechanism i.e., five-thirds of a ton minus two-thirds of a ton.

Thus in this example the load required to release the lower spring is one-third of a ton and the load to release the upper spring is five-thirds of a ton. Similar calculations can apply to any number of tower sections.

Accordingly the invention provides a telescoping crane construction in which the latch mechanisms provided ensure that the uppermost tower section is contracted first followed successively by contraction of next lower sections one after the other. On extension of the tower the lowermost of the extending sections is extended first carrying with it the other telescoped sections whereafter further sections are extended in turn with the uppermost section being extended last.

What we Claim as our invention and desire to secure by Letters Patent is:

1. A crane including a generally vertical boom which comprises at least three sections, namely first, second and third sections, telescopically associated for relative movement between contracted and extended condition, and in the extended condition of which the first section is the uppermost of the three sections and the third said section is the lowermost, an extension cable operatively interconnected between the respective said sections for extending same in response to tensioning of the cable, latch mechanism carried by each of the first and second of said sections for lateral movement into and from locking engagement with an adjacent said section to interlock said sections in their extended relationship, a portion of said extension cable extendingfin a generally vertical path, a latch release bar guided or generally horizontal movement on each of said first and second sections and linked to the latch mechanism of the respective sections for releasing said mechanism, responsive to horizontal movement of the respective bars; spring means resiliently urging said respective bars horizontally toward operative positions to engage v the latch mechanisms, each said release bar extending transversely to said cable portion of its respective section and having means thereon for engaging and laterally deflecting said portion of the extension cable when the release bar is in said operative position under the influence of its spring means, each said release bar being retractable horizontally to a position for releasing its associated latch mechanism responsive to the application of tension to said extension cable in an amount sufi'icient to overcome the latch engaging pressure exerted thereon by its spring, each said latch mechanism of the uppermost section, when in locking engagement with said second section, supporting the uppermost section on said second section and being normally maintained in locking engagement by the weight of the uppermost section, the tensioning of said extension cable sufficiently to raise the uppermost said section to permit release of its said latch mechanism, being insufficient to raise said second section with the first section.

2. A crane as defined in claim 1, including second latch mechanisms carried by the respective sections for interlocking each said section with an adjacent said section in the contracted condition of said boom, and means responsive to a predetermined tension in said extension cable for releasing each of said last mentioned latch mechanisms.

3. A crane as defined in claim 1, including means for adjusting the effective strength of the respective springs and thus the tension at which the said extension cable releases the respective latch mechanisms. 

1. A crane including a generally vertical boom which comprises at least three sections, namely first, second and third sections, telescopically associated for relative movement between contracted and extended condition, and in the extended condition of which the first section is the uppermost of the three sections and the third said section is the lowermost, an extension cable operatively interconnected between the respective said sections for extending same in response to tensioning of the cable, latch mechanism carried by each of the first and second of said sections for lateral movement into and from locking engagement with an adjacent said section to interlock said sections in their extended relationship, a portion of said extension cable extending in a generally vertical path, a latch release bar guided for generally horizontal movement on each of said first and second sections and linked to the latch mechanism of the respective sections for releasing said mechanism, responsive to horizontal movement of the respective bars; spring means resiliently urging said respective bars horizontally toward operative positions to engage the latch mechanisms, each said release bar extending transversely to said cable portion of its respective section and having means thereon for engaging and laterally deflecting said portion of the extension cable when the release bar is in said operative position under the influence of its spring means, each said release bar being retractable horizontally to a position for releasing its associated latch mechanism responsive to the application of tension to said extension cable in an amount sufficient to overcome the latch engaging pressure exerted thereon by its spring, each said latch mechanism of the uppermost section, when in locking engagement with said second section, supporting the uppermost section on said second section and being normally maintained in locking engagement by the weight of the uppermost section, the tensioning of said extension cable sufficiently to raise the uppermost said section to permit release of its said latch mechanism, being insufficient to raise said second section with the first section.
 2. A crane as defined in claim 1, including second latch mechanisms carried by the respective sections for interlocking each said section with an adjacent said section in the contracted condition of said boom, and means responsive to a predetermined tension in said extension cable for releasing each of said last mentioned latch mechanisms.
 3. A crane as defined in claim 1, including means for adjusting the effective strength of the respective springs and thus the tension at which the said extension cable releases the respective latch mechanisms. 